University of California

City of Hope

Other

Chiron Viagene, Inc.

Jiing-Kuan Yee

Theodore Friedmann

Shin-Tai Chen

Jane C Burns

Douglas J Jolly

Wen-Hwa Lee

Jack R Barber

Charles E Prussak

Atsushi Miyanohara

Eva Y H P Lee

Gilles H Michel

Huei-Jen Sue Huang

Gilles Michel

Nobuhiko Emi

Murine leukemia virus (MLV) and lentivirus vectors have been used previously to deliver genes to hematopoietic stem cells (HSCs) in human gene therapy trials. However, these vectors integrate randomly into the host genome, leading to disruption or inactivation of vital host genes. The present invention discloses a novel lentiviral vector system that overcomes this problem by integrating into a host genome in a site-specific manner.

Lentiviral vectors for site-specific gene insertion

A method for gene therapy for cancers wherein chromosomal location of an inactive or defective cancer suppressing gene is established, a replacement gene which is preferably cloned is then used to replace the inactive or defective cancer suppressing gene in the chromosome. In addition to its uses in therapy, the present invention provides a means for prophylactically treating individuals having a genetic predisposition to cancer and provides an animal model for testing for carcinogenicity of environmental substances.

Products and methods for controlling the suppression of the neoplastic phenotype

The present invention features compositions and methods for the inducible expression of a polypeptide, especially a polypeptide normally cytotoxic to the eukaryotic host cell in which it is to be expressed. A nucleotide sequence encoding a polypeptide of interest is operably linked to an inducible promoter. Expression from the inducible promoter is regulated by a multi-chimeric transactivating factor, composed of a first ligand-binding domain that negatively regulates transcription, a transcriptional activation domain, and a second ligand-binding domain that positively regulates the transcriptional activation function of the transactivator. Transcription of the nucleotide sequence under control of the inducible promoter is activated by the multi-chimeric transactivator when both the ligand that binds the first ligand-binding domain is absent and the ligand that binds the second ligand-binding domain is present. This inducible expression system is particularly useful in the expression of the cytotoxic protein VSV G for the production of pseudotyped retroviral vectors.

Inducible expression system

The present invention features compositions and methods for the inducible expression of a polypeptide, especially a polypeptide normally cytotoxic to the eukaryotic host cell in which it is to be expressed. A nucleotide sequence encoding a polypeptide of interest is operably linked to an inducible promoter (e.g, a promoter composed of a minimal promoter linked to multiple copies of tetO, the binding site for the tetracycline repressor (tetR) of the Escherichia coli tetracycline resistance operon Tn10). Expression from the inducible promoter is regulated by a multi-chimeric transactivating factor, composed of a first ligand-binding domain that negatively regulates transcription (e.g., a prokaryotic tetracycline repressor polypeptide), a transcriptional activation domain, and a second ligand-binding domain that positively regulates the transcriptional activation function of the transactivator (e.g., a ligand-binding domain of a steroid receptor, preferably an estrogen receptor (ER)). Transcription of the nucleotide sequence under control of the inducible promoter is activated by the multi-chimeric transactivator when both the ligand that binds the first ligand-binding domain (e.g., tetracycline) is absent and the ligand that binds the second ligand-binding domain (e.g., a steroid) is present. This inducible expression system is particularly useful in the expression of the cytotoxic protein VSV G for the production of pseudotyped retroviral vectors.

An enveloped vector particle contains gag and pol proteins from a retrovirus, a nucleic acid sequence and an envelope that includes VSV G envelope glycoprotein. The vector particle can be used to introduce nucleic acids into cells.

VSV G pseusdotyped retroviral vectors

The present invention features packaging cell lines and recombinant retroviral particles produced thereby, particularly pseudotyped retroviral particles. Preferably, the packaging cell lines are derived from HeLa, Cf2Th, D17, MDCK, or BHK cells, most preferably from Cf2Th cells. Retroviral particles are produced by inducibly expressing an envelope protein of interest (e.g., a retroviral envelope or the envelope protein of vesicular stomatitis virus (VSV G)). Inducible expression of the envelope protein is accomplished by operably linking an envelope protein-encoding nucleotide sequence to an inducible promoter (e.g., a promoter composed of a minimal promoter linked to multiple copies of tetO, the binding site for the tetracycline repressor (tetR) of the Escherichia coli, tetracycline resistance operon Tn10). Expression from the inducible promoter is regulated by a multi-chimeric transactivating factor, composed of a first ligand-binding domain that negatively regulates transcription from the inducible promoter (e.g., a prokaryotic tetracycline repressor polypeptide (tetR)), a transcriptional activation domain, and a second ligand-binding domain (e.g., a ligand-binding domain of a steroid receptor, preferably an estrogen receptor (ER)).

Packaging cell lines for pseudotyped retroviral vectors

The present application discloses retrovirus-derived vectors in which the retroviral envelope glycoprotein has been replaced by the G glycoprotein of vesicular stomatitis virus, and the use of these vectors in the transfer of exogenous genes into the cells of a wide variety of non-mammalian organisms. Also disclosed is a method for the generation of retroviral vectors in high titers, wherein a recombinant, stable host cell line is provided which harbors the retroviral vector of interest without envelope protein. High-titer retroviral vector production is initiated by introducing nucleic acid encoding a functional membrane-associated protein into the cell line. The vectors disclosed in the present application can be concentrated by ultracentrifugation to titers greater than 10.sup.9 cfu/ml which are especially useful in human gene therapy trials, and can also infect cells, such as hamster and fish cells, that are ordinarily resistant to infection with vectors containing the retroviral envelope protein.

Growing community of inventors

Del Mar, CA, United States of America

Jiing-Kuan Yee